The present invention relates generally to attenuation of vibrations imparted to a support.
Support of equipment, having a source of vibration associated therewith, on a substructure surface by attachment thereto through a vibration isolation mount has been utilized to reduce the vibratory force impinging on the surface. Complete isolation is never achieved however because compliance or softness of the mount is necessarily limited in order to obtain adequate positional tolerance for the equipment being supported on the surface. It is therefore an important object of the present invention to provide support for such equipment loads on a surface through a vibration isolation mount with adequate positional tolerance, while permitting a reduction in vibration inducing forces transmitted therethrough.
In accordance with the present invention, the cylindrically shaped, viscoelastic component of the vibration isolation mount is interfaced throughout with a stiffening sleeve to restrict its bulging type distortion so as to strictly maintain positional tolerance for the equipment being supported. The sleeve is however made of a piezoelectric ceramic material so that it may be electrically excited under selective control to null its distortion restricting effect on the viscoelastic cylinder and reduce vibration inducing force while the equipment being supported is undergoing vibration within an operational frequency range. Toward that end, vibration of the supporting surface is continuously sensed so that when the vibration detected is within the operational frequency range, an electrical error signal is applied by a controller to the stiffening sleeve to institute said electrical excitation thereof through the controller as an active actuator for reducing vibrations.